In the production of hydrocarbons from hydrocarbon-bearing unconsolidated formations, a well is provided which extends from the surface of the earth into the unconsolidated, or poorly consolidated formation. The well may be completed by employing conventional completion practices, such as running and cementing casing in the well and forming perforations through the casing and cement sheath surrounding the casing, thereby forming an open production interval which communicates with the formation.
The production of hydrocarbons from unconsolidated or poorly consolidated formations may result in the production of sand along with the hydrocarbons. Produced sand is undesirable for many reasons. It is abrasive to components within the well, such as tubing, pumps and valves, and must be removed from the produced fluid at the surface. It may partially or completely clog the well, thereby making necessary an expensive workover. In addition, the sand flowing from the formation may leave therein a cavity which may result in collapsing of the casing.
Probably the most widely-used technique to control the production of sand from a formation is known as gravel packing. A gravel pack is formed in the well adjacent to part or all of the unconsolidated or poorly consolidated formation exposed to the well. The gravel is sized so that it forms a permeable mass which allows flow of the produced hydrocarbons therethrough and into the well while blocking the flow of sand produced with the hydrocarbons. While gravel packing can effectively control sand production, it can reduce well productivity, increase well cost, and necessitate workovers.